Cut ring expander



NOV. 29, 1949 KUERT 2,489,905

CUT RING EXPANDER Filed Sept. 17, 1946 QJMIKLQMM A TTORNE Y5 PatentedNov. 29, 1949 CUT RING EXPANDER Fritz Kuert, Winterthur, Switzerland,assignor to Sulzer Freres, Societe Anonyme, Winterthur,

Switzerland Application September 17, 1946, Serial N 0. 697,532 InSwitzerland December 18, 1945 6 Claims.

This invention relates to a device for expanding cut rings, inparticular piston rings, and is characterised by an expanding tongs andtwo gripping arms, each of the latter having a gripping piece to holdone end of the ring and each being connected by two links to an arm ofthe expanding tongs.

It is preferable to construct the device in such a way that each arm ofthe expanding tongs, together with the gripper arm linked to it and thelinks, forms a parallelogram. One of the links to each gripper arm andthe two arms of the expanding tongs can have one common pivot point. Thearms of the expanding tongs may however also be linked to a connectingbody at separate places but in positive running engagement with eachother.

The invention is further explained below through two simplifiedembodiments of it shown in the drawing. Fig. 1 shows an expander inwhich each arm of the expanding tongs, together with the gripper armlinked to it and the links, forms a parallelogram. Fig. 2 illustrates anexpander in which the arms of the expanding tongs are linked at separatespots to a connecting body 55 but are in positive running engagementwith each other. 7

The expanding device shown in Fig. 1 has a two-armed expanding tongs,the arms l of which form lever arms, and two gripper arms 2. Each of thegripper arms 2 is fitted at one end with an elongated gripper 3 whichextends lengthwise therefrom for holding the end of the cut ring 4. Eachgripper arm 2 is linked at two points 5 and 6 to two spaced links 1 and8 of substantially equal length, whilst these links in their turn arepivotably connected at the points 9 and ID to a lever arm of theexpanding tongs. Except for the pivotal connections 5 and 6, and 9 andIll, the links 1 and 3 are unrestrained. The distances between points 5and 6 are the same as the distances between points 9 and I0. Each leverarm I of the expanding tongs consequently forms with the linked-ongripper arm 2 and the respective links 1 and 8 a parallelogram whoseangle may be altered as desired when the gripper 3 is not in use. Thedistance between the two grippers 3 may in this way be suited to thedistance between the two ends of the ring. The front links I and the twolever arms I of the expanding tongs are linked together at the commonpivot point 9. The tongs are opened out by means of a spindle llprovided with left hand and right hand screw threads and running in nutsl2 and I3 pivotably connected to the lever arms of the tongs.

2 r When using the expanding device, with the lever arms I of the tongsapproached to each other, each of the grippers 3 is brought over an endof the ring 4. By causing the lever arms I of the tongs to spread apartby means of the spindle II, the angular position of the gripper arms 2with respect to each other is changed. In consequence of the possibilityof altering the angles of the parallelogram, the distance between thegrippers remains unchanged; it is always equal to the distance betweenthe ends of the rings until the fingers l4 and I5 come both to rest onthe surfaces of the ring ends. Until the fingers come into thatposition, no forces are exerted by the tongs on the ring. As shown inthe drawings, the finger l4 engages an inner-face portion of the ringwhile'the finger l5 engages the outer periphery of the ring at adistance spaced from its adjacent cut end.

If the expanding tongs is opened further, from the moment when thefingers come to lie on the ends of the ring, each of the grippers exertson the ring end held by it two equal but opposite couples. Single forcesare not exerted by the grippers on the ends of the ring, since thedistance between the two gripper arms can at any time suit itself to thedistance between the ends of the rings without any resistance. Inconsequence of the action of the couples, the ring 4 will be openedagainst its elastic forces. Then each cross-section of the ring 4 willbe stressed only by a pure bending moment, but not by any lateral pullor pressure. It is thus possible, in the case of piston rings (or in thecase of other rings which have for instance to be inserted into groovesor removed from them), to prevent over-stressing because of the actionof unsuitable forces when opening them.

In the device illustrated in Fig. 2, the two lever arms I of the tongsare not linked together at one common pivot point, but separately to twopoints l6 of a connectingpiece I1 and kept in positive runningengagement with each other through meshing gear segments. The gripperarms 2 are in linked connection with the points Ill and I8 of the leverarms I of the tongs through two links 1 and 8 of different lengths.

The lever arms I of the expanding tongs are opened by a pressing tongsconsisting of two arms l9 and 20 pivoted at 24 and held open by spring24 which are linked at the points 2| and 22 to the lever arms of theexpanding tongs. By pressing the two handles l9 and 20 of the pressingtongs together the lever arms of the expanding tongs are opened and aring is thereby expanded.

According to the dimension chosen for the distance between the two pivotpoints IS on the connecting piece H, the length of the links 1 and 8 andthe distances between the pivot points 5, 6, l and I8, a single forcecorresponding to requirements can be exerted also on the ring elements,and this may lead to a more -favourable distribution of the stresses inthe case of special rings.

I claim:

1. An expanding tong device for insertion into an opening and exertingoutward pressure on opposite sides thereof including a :pair of leverarms, means connecting the lever arm's for;pivota'l motion with respectto one another, a pair of elongated pressure members, one .pressuremember extending in the same general direction as one of the lever armsand the other pressure member extending in the same general direction asthe other lever arm, a pair of separate links pivotally nonnecting eachpressure member to its correspondih'g leVerarm, eachl-ink beingfreelyspivoted at 'one end to-"apressure nrember and atits other end tothe-corresponding lever arm, corresponding *ends of the pressure membersbeing {positionable adjacent one another, andmeansa'tsaid corresponding"end of each lpr-essure member -for engaging "the corresponding side ofthe opening into "which it is inserted :to cooperatively securefithat-end 6f thatzpressure :m'emb'er tOsaidcOrr'es'iiondingside'of theoperiing.

2. expanding tdng device as llefined in 'ciaiih l in =iivliich aparallelogram is formed by each -le'ver arm together with :itscorresponding :pre's'sufe member "and '"the links connectin'g them. *3.:"An expanding t'ohg device as defined in cl'aim 1 in'wliichpneoftlielinks of each pair "and the '-:two -Ieverar-ms are connected at "acommon point. 4. An expanding tong device "as defiired in Fcraim 1 inwhich the pivotal connection between the Il/e' arm's "Comprises "a1001151 and separate s'pacedpiv" sfor'ea'oh lever arm and which*l-ild'e's iii" 'h'ga'g-ihg portions onth'e level arms ro 'con oimovementoftnem.

5. A out ring expander co'mprising a p'air of Te'if'r arfii's,meansconnecting the lei/e1 alfmsTGr Di-Vdtal indtfdn with respect toOh'e another, "a

painofeiohgated gripper members, one gri per member extending in thesame general direction as one of the lever arms and the other grippermember extending in the same general direction as the other lever arm, apair of otherwise unrestrained separate links pivotally connecting eachgripper member to its corresponding lever arm, each link being ,pivotedat :one end to a gripper mem'ber and at its other "end to thecorresponding lever arm, corresponding ends of the gripper members beingpositionable adjacent one another, and means at said corresponding endsof each 'gripp'ef'member for securing that end of that grippermember toanend of a cut ring.

6. A cut ring expander comprising a pair of lever arms, means"connecting the'lever arms for ,pivotal motion with respect to oneanother, a .pair of elongated gripper members, one gripper memberextending in the same general direction as one of the lever arms and theother gripper member extending in the same general direction as theother lever arm, aipair of separate links pivotally connecting eachgripper member to its corresponding lever arm, each link being freelypivoted atone 'end "toa sgrip'per member and at its oth'er erid to'theoorresponding lever arm, each -01 "saidigripp'ermembers having at oneend thereof a finger extending therefrom in a, direction generallylongitudinally of the gripper :member, the distal -end of 'ea'ch fing erhaving an overhanging 'p'rfition'lext'ending therefrom to engage aninner face -portion :bf a cut ring adjacent one end there'o said end Cofea'ch :gripper member also having 'a portion "spaced irom the fingerthereof in adirectiongeneraliy transversely of the gripper nfember :tobear on the outer periphery of "the ring at a distance f-rom su'ch endthereof FRITZ KUERT.

CITED 'Tli'e "renewing rbferences are of record in the file of thispatent:

STATES PATENTS Number Name Date -1,466;659 'Kabanuck Sept. 4, 19231,718,121 Denton June 18, 1929 1,760,980 Foreman June 3, 1930 133081064:Pe'a'rinan 'et a1. June 2, 1931

